Research Letter

 SCHOOLBAG WEIGHT AND MUSCULOSKELETAL SYMPTOMS IN NEW ZEALAND SECONDARY SCHOOLS 

Stephen Legg, Jannine Whittfield, Duncan Hedderley, David Stubbs

Centre for Ergonomics, Occupational Safety and Health, Massey University, New Zealand and
Robens Centre for Health Ergonomics, European Institute of Health and Medical Sciences, University of Surrey, UK.

This research letter is presented as an example of the international collaboration between the Master of Ergonomics programme, Centre for Ergonomics, Occupational Safety and Health, Massey University, New Zealand and the Master of Health Ergonomics programme, Robens Centre for Health Ergonomics European Institute of Health and Medical Sciences, University of Surrey, UK. The study was conducted in Auckland, New Zealand by Jannine Whittfield in partial fulfilment of an MSc in Health Ergonomics, University of Surrey. It was jointly supervised by Associate Professor Stephen Legg (New Zealand) and Professor David Stubbs (UK). The study has resulted in one conference presentation and two refereed papers (see references).

 
The average weight of schoolbags (6.6 kg, 11.7% of body weight) carried by secondary students in five New Zealand schools exceeded recommended international industrial guidelines for handling of loads by adults and the prevalence of musculoskeletal symptoms amongst the students was high. We believe there is a need for secondary schools to develop specific strategies to reduce the physical strain associated with carriage of schoolbags by their students in order to help prevent the onset and development of musculoskeletal symptoms.

Carrying schoolbags may contribute to low back pain in children (Troussier et al. 1994). Despite the proposal of an unofficial (and scientifically unproven) limit of 10% of bodyweight (Voll and Klimt 1977), it has been reported that German (Voll and Klimt 1977) and in Italian (Negrini et al.1999) schoolchildren carry schoolbags weighing between 11-14% and 22% of body weight respectively. In the Italian study the average daily schoolbag load was 9.3 kg. This exceeded international manual handling guideline limits for adults (Health and Safety Executive 1992, Waters et al. 1993). No previous studies appear to have assessed both schoolbag weight and musculoskeletal symptoms simultaneously nor explored the nature of the loads carried. We have therefore examined the weight and use of schoolbags and the prevalence of musculoskeletal symptoms associated with schoolbag carriage amongst 140 secondary school students (70 third form students comprising 35 females and 35 males, and 70 sixth form students comprising 35 females and 35 males) from five New Zealand schools (Whittfield and Legg 1999, Whittfield et al. 2001, 2003). 

All subjects were informed of the procedures of the study and consented to their voluntary participation. The body weight of each student was measured, as were the weight of their schoolbags and the weight of any additional items that they carried. 
The students answered a questionnaire that enquired about the type of schoolbag carried, the mode of carriage and the duration of schoolbag carriage. The questionnaire also requested details about additional items carried and the availability and use of lockers or storage space at school. Additional questions based on a modification of the standardised Nordic musculoskeletal questionnaire and a picture of the human body with nine body regions (neck, shoulders, upper arms, lower arms, upper back, lower back, upper legs, knees, lower legs) enquired about musculoskeletal symptoms experienced in the week immediately preceding data collection. The students were asked to answer ‘yes’ or ‘no’ to the question, “Have you, at any time in the last seven days had any ache, pain, discomfort or numbness that may be as a result of your schoolbag(s)?” for each of the nine body regions.

The average schoolbag weight of 7.0 kg (13.2% of body weight) for third form students (mean age, height and body weight: 13.6 yr, 162.7 cm and 54.7 kg) was significantly (p<0.001) greater than that of 6.3 kg (10.3% of body weight) for sixth form students (mean age, height and body weight: 17.1 yr, 169.4 cm and 62.9 kg). The average loads carried by male and female students respectively were 6.8 and 6.5 kg (11.5 % and 12.0% of body weight). The most extreme case in this study was a third form male student who carried 13.5 kg (27.0% of his body weight). This consisted of a schoolbag weighing 9.5 kg and an additional bag weighing 4.0 kg. The overall mean schoolbag weight of 6.6 kg (11.7% of body weight) exceeded the load that would be recommended for adult industrial manual materials handling under similar conditions by the United Kingdom Health and Safety Executive (4.5 kg) (1992) and was very close to that of United States guideline limit (6.8 kg) (Waters et al.1993). It also exceeded an unofficial recommended upper limit of 10% of body weight (Voll and Klimt 1977) for children.

The most common type of schoolbag was a backpack (89.3%). This was predominantly carried on both shoulders (70.7%) although bags were also carried on a single shoulder (10.7%), swapped between both shoulders and one shoulder (15.7%) or in their hands (0.7%). Students carried a variety of other bags including sports bags (7.9%), shoulder bags (2.2%) and cloth carry bags (0.8%). 

The mean length of time that schoolbags were carried was 84.8 (SD 52.5) minutes per day. Third form students reported carrying their schoolbags 30.3 minutes longer per day (p<0.001) than the sixth form students. They also reported carrying more items in addition to their schoolbags and had less access to lockers to store their books and supplies than sixth form students. Only one of the schools provided lockers for third form students - but only to 57.1% of them, whereas four of the schools provided lockers for sixth form students. 

Musculoskeletal symptoms were reported by 77.1% of the students and were most prevalent in the following locations: neck (44.3%), bilateral shoulders (43.6%), upper back (36.4%) and lower back (35.0%). Neck, shoulder and upper back symptoms were reported more often by female students than males. Low back symptoms were more common amongst sixth form students than third form students. The self reported prevalence of musculoskeletal symptoms amongst these students was considerably higher than in other known high risk groups and would therefore warrant further investigation in the future. 

The results of our study suggest that secondary school students and particularly third form students are at risk of developing musculoskeletal symptoms. Heavier schoolbags, longer carriage durations, the carriage of additional bags and the lack of access to lockers amongst third formers could contribute to the production or maintenance of musculoskeletal symptoms in the younger students. Based on these findings we believe that specific strategies need to be developed to help prevent the onset and development of musculoskeletal symptoms in secondary school students.

Health and Safety Executive, Manual Handling Operations Regulations. London: Her Majesty’s Stationery Office. 1992.

Negrini S, Carabalona R, Sibilla P. Backpack as a daily load for schoolchildren. Lancet 1999; 354: 1974.

Troussier B, Davoine P, de Gaudemaris R, Fauconnier J, Phelip X. Back pain in schoolchildren: a study among 1178 pupils. Scand J Rehab Med 1994; 26: 143-46.

Voll, H J, Klimt, F. Die beanspruchung des kindes durch die schultasche. Offentliche Gesundheitswesen 1977; 39: 369-378.

Waters TR, Putz-Anderson V, Garg A, Fine LJ. Revised NIOSH equation for the design and evaluation of manual lifting tasks. Ergonomics 1993; 36(7): 749-776.

Whittfield J and Legg SJ. Schoolbag weight and musculoskeletal symptoms in New Zealand secondary schools. Proceedings of the 9th New Zealand Ergonomics Society Conference, Christchurch, New Zealand, pp 76-79, 25-26 November, 1999. 

Whittfield J, Legg SJ and Hedderley DI. The weight and use of schoolbags in New Zealand secondary schools. Ergonomics 2001;44 (9): 819-824. 

Whittfield J, Legg SJ and Hedderley DI. Schoolbag weight and musculoskeletal symptoms in New Zealand secondary schools. Applied Ergonomics 2003; in press.


Mean (SD) schoolbag weight (kilogrammes (kg) and as a percentage of body weight (%BW)) for 140 secondary school students

* p<0.05, *** p<0.001 for differences between 3rd and 6th form students